Hello Adrienne
I would say that you are quite early to plant PSB. I planted mine too early last year and I had giant plants as a result, as tall as me (ok 5 feet tall) with huge trunks!
My crop was no better than my friend who planted her in august. Her plants were small but had the same amount of purple sprouting.
My advice would be not to plant too many -or plant different varieties that crop at different time.
There’s lots of brassicas you can plant end of June/July/August: rapa (a kind of broccoli, super fast grower) kale, pak choi, tatsoi (tasty mustard for stir fry), red cabbage, green cabbage, cauli, parley, rocket. You ca also plant beetroots, carrots, peas and beans.
Ness